Trying to trace source of non-working op-amps

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Hi,

We bought some TL074 op-amps a while ago. We have built up over a
100 boards, and we now find that the TL074 devices are not working at
all. If we replace the device with a genuine TI TL074 device, or any
other OpAmp the board works as required. The non-working TL074 devices
has a "FAT" F as the logo. Are there any sites where one can search
for a manufacturer based on the logo they put on their devices ?

Regards
  Anton Erasmus

Re: Trying to trace source of non-working op-amps

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A quick google search on "electronics manufacturers logo" yields the
following as the 4th link.

http://www.chipdocs.com/logos/logotypes.html

Only "F" I see there is Fairchild Semiconductors, which was my first guess
anyway.

HTH

--
Richard

Re: Trying to trace source of non-working op-amps
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<http://www.elektronikforum.de/ic-id/

Fairchild or Fujitsu.

Re: Trying to trace source of non-working op-amps

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Hi,

Thanks for the response. I could also only find Fairchild with an F
logo. I was hoping for some site with maybe more obscure manufacturers
logos. The component suppliers here in South Africa sometimes buy from
extremely odd places for "standard" components. (74 series, Op-Amps,
4000 series etc.) Sometimes these companies have logos that on first
glance are quite similar to the main stream semiconductor logos.
Unfortunately even though we specificially specify the more main
stream seimconductor part numbers, it sometimes happen that the buyers
get told by the suppliers that the component is an exact equivalent at
a 10th of the price, and they cannot resist.
Most of the time this is not a problem, but if these devices are
really from Fairchild Semiconductors (a company from I do not expect
or suspect of supplying dofgy devices), then I need to find out the
problem.

Regards
   Anton Erasmus




Re: Trying to trace source of non-working op-amps

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When the opamp is "not working at all" what voltage do you see at
the plus input, the minus input and the output?  If you put the
opamp in a test circuit, does it work (in other words are they only
bad when installed on your board or always bad)?



--
Guy Macon, Electronics Engineer & Project Manager.  Remember Doc Brown
from the 'Back to the Future' movies?  Do you have an "impossible"
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Re: Trying to trace source of non-working op-amps
On Fri, 10 Oct 2003 11:10:25 +0000, Guy Macon
<http://www.guymacon.com/ wrote:

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Hi,

The circuit is a stock standard non-inverting amplifier with a gain of
about 20. This particular board has been manufactured in batches of
100 every 3 months or so for the last 10 years. We have had  problems
with dodgy TL074s once before, but then the components came from
some obscure semiconductor house in India. With the non-inverting
Amp isolated from the rest of the circuit, then one basically get
nothing out no matter what the input is. The chips seems completely
"dead". Replacing the chip with a TL074 from TI, or with any other
quad op-amp we had lying around, then the circuit works as expected.
We have had ICs from obscure semiconductor houses in the past, who's
logos at first glance looks very much like the "Big" semiconductor
houses. The dodgy TL074s logos looks like Fairchild Semicondcutor's.
I have never experienced or even heard of Fairchild's devices working
other than as specified. If I can establish from where these devices
came, then I can at least try and ensure that we do not buy from that
supplier again.

Regards
  Anton Erasmus


Re: Trying to trace source of non-working op-amps
Hi Anton,

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Is this device in a very tiny surface-mount package, with abbreviated
package markings? Are you sure that the chips you bought before are
actually TL074s?

Listed vendors for the TL074 are:

ST Microelectronics
Motorola Semiconductor Products
ON Semiconductor
Texas Instruments

also:

National Semiconductor (M38510/11906BCA, military version)

None of those has a logo that looks like an "F"...

Re: Trying to trace source of non-working op-amps
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Component subsitution is becoming a problem, particularly with common garden
variety parts, and suppliers who aren't authorised dealers. They may be
manufacturered by dodgy component makers who may have a very basic semiconductor
manufacturing facility set up, or the components may be castoffs from the major
semi manufacturers that didn't come up to spec at various testing stages and
were
stolen/sold off to experimenters/whoever. They may even be legitimate cheaper
components
that have had their correct markings removed, and markings of a more expensive
component substituted.

Some examples of fake components have been power transistors that were used in
audio
amplifier kits here in Australia. These had markings that at first glance
indicated
that they were made in Mexico, but when you looked closer, it actually said
"MEX1CO",
ie. substituting a "1" where an "I" should have been. When the amplifier was
first
turned on/cranked up, the output transistors destroyed themselves. The owner
usually
went back to the shop where they bought the kit, and purchased replacement
transistors.
More often than not, accidently purchasing more fakes, until the the method of
identification
was found.

Fake pentium cpus have been getting around for years.
http://www.heise.de/ct/english/97/01/018 /

The only way to be assured of purchasing genuine components is to deal ONLY with
the
manufacturer, or it's legitimate representatives.

--

Regards
David

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